HELP NEED ADVICE !

I gave birth to a baby girl a week ago my so had previous arguements about him texting & talking to other women while i was pregnant , & he said he will stop yesterday as im changing my daughters diaper , i see that he was texting another woman asking her why is she ignoring him & what are they doing this sat . He works five days a week tues-sat i confront him about it & he says she is just a friend she has a kid & lives w/ her boyfriend. & i ask to see his phone he told me no this is the second time he as told me no that i shouldnt see his phone . I broke up w/ him & me & my daughter are moving in w/ my father , i dont know if he lies to me & says he is working late . & going to see her . I dont know what to do . Am i over exaggarating the situation ? Should i take my daughter ?